The broad goal of NASA's Space Life Sciences Division Advanced Human Technology Program (AHST) is to support the research and development that will allow humans to explore and live in space safely and efficiently.  The mission of its Advanced Environmental Monitoring and Control Program (AEMC) is to "provide spacecraft with advanced, microminiaturized networks of integrated sensors" to monitor and control the environment. One of the main components of the AEMC program is the development of advanced technologies for monitoring the chemical and physical status of life support systems and their resources. One critical component of this system is the water supply.  All water which can come into contact with humans, internally or externally, must be either continuously or regularly monitored.  The in-situ or on-line monitoring systems must provide a reliable measure of water quality by identification and quantification of a broad spectrum of chemical components, especially potentially toxic pollutants.

The overall goal of this research project is to understand the principles, concepts, and science which will enable the development of an integrated, rugged, reliable, low mass/power, electroanalytical device which can identify and quantitatively determine a variety of water quality parameters including, inorganics, organics, gases, pH, ORP, and conductivity.

To accomplish these goals our group at Tufts, in collaboration with the NASA's Jet Propulsion Laboratory and ThermoOrion Research, is undertaking the reseach necessary to to lead to an electrochemically-based integrated array of chemical sensors based on several novel transduction and fabrication concepts.  Even though this type of sensor array might be thought of as an "electronic tongue", it is exceedingly more capable.  Working in conjunction with a neural network, it will provid both qualitative and quantitative information for a much broader range of components (cations, anions, inorganic and organic) than a human tongue ever could.
 

The microfabrication, integration, and multiplexing of such a large number of these sensors on a single substrate has not been previously attempted and presents a formidable scientific and technical challenge.  Our work has led to the discovery of a unique electro-immobilization technique which imparts special selectivity properties to each sensor.  Unlike previous devices though, this electrochemically based sensor will provide both identification and reliable quantitative data.  The use of an integrated set of species selective ion selective electrodes (ISE), requires that we simultaneously address several fundamental scientific questions, especially in terms of the scaling of these transduction mechanisms, the electrofabrication process, and the selection and deposition mechanisms of the appropriate matrices and polymer substrates.

This technology resulting from this research project could have a significant impact on the ability of humans to conduct long-duration space flight missions safely, enable more efficient exploration of the low-Earth-orbit environment in which the International Space Station operates, and also be used in exploration of the solar system beyond Earth orbit.